5HTT Genotyping

Serotonin is a neurotransmitter, a chemical that transmits signals from one nerve cell to another, and changes in the levels of this chemical have been associated with some behavioral disorders. Certain psychiatric medications help treat these disorders by targeting 5HTT, a protein that helps naturally regulate serotonin levels. However, genetic changes to 5HTT can decrease the effectiveness of these medications and increase the risk of adverse effects.

Indication for Testing

Patients who are initiating SSRI or other 5HTT-targeting therapies, or experiencing adverse effects or low efficacy should consider 5HTT genotyping.

Specimen Information
Please call Client Services at 800-523-6487 to obtain specimen kits.

Buccal Swabs: 4 sterile buccal swabs
Blood: 5-10 cc whole blood lavender-top EDTA or Yellow-top ACD-A tubes
Turnaround Time:  5 days, 4 day STAT

CPT Codes

(provided for guidance only)
5HTT Mutation DNA Analysis:  81479

Clinical Significance

The clinical utility of 5HTT is still under development. Evidence shows that polymorphisms may play a part in disorders such as sudden infant death syndrome, Alzheimer’s, and depression, and may affect psychomotor stimulant and SSRI.
The most significant 5HTT polymorphism is the short (S) allele, with normal variants being known as long (L) alleles. The S allele may cause individuals to be more likely to fail SSRI therapy or experience adverse effects because fewer SSRI binding sites are available, which may result in the rapid accumulation of serotonin.iii, iv, v Racial variations exist, with results for Caucasians having obtained the most conclusive results regarding efficacy.

Significant Polymorphism: S allele
Significant Inhibitors/Inducers: None

Prevalences:

• Short/Short (S/S): Poor 5HTT
  • Caucasian: 16.7%
  • Asian: 60.2%
  • Other/Mixed: 30.4%

• Short/Long (S/L) Intermediate 5HTT
  • Caucasian: 46.3%
  • Asian: 35.1%
  • Other/Mixed: 49.6%

• Long/Long (L/L) Normal 5HTT
  • Caucasian: 37%
  • Asian: 4.7%
  • Other/Mixed: 20%